The present invention generally relates to an information recording and reproducing apparatus, and more particularly to an apparatus for recording and reproducing information on and from a rotary recording medium such as an optical disc and an optical magnetic disc using a light beam emitted from a light source such as a laser diode.
In a conventional information recording and reproducing apparatus, the intensity of a laser beam is controlled so as to be fixed to a constant level. Then, information is recorded and reproduced on and from a disc such as an optical disc and an optical magnetic disc by using the laser beam.
There are delicate differences of recording sensitivity in every disc and differences of environment temperature in every recording time so that the conditions for recording information on the disc change for every disc and every recording time. Thus, it is difficult to always record information under the best conditions. As the result of this, there is a disadvantage in that there are cases where frequent errors occur at the time of reproducing information. There is also a disadvantage in that there is the possibility that the life of information recorded on the disc will become short. That is, the time during which information recorded on the disc is held on it will become short.